System and method for use in photoplethysmography

Abstract

A system for use in monitoring application is described. The system comprises a light detection unit and an illumination arrangement. The detection unit is configured for collecting light returning from a selected inspection region for determining variations in collected light intensity. The illumination arrangement comprises one or more light sources configured for providing illumination of a selected wavelength range directed toward said inspection region. Wherein the illumination arrangement is arranged around the detection unit to provide symmetrical illumination conditions with respect to an axis connecting said detection unit and said inspection region.

The invention claimed is: 
     
       1. A system comprising: an illuminator for illuminating a selected inspection region with light of a selected wavelength range, and at least one light detector defining a detection path connecting said at least one detector and said selected inspection region and being configured for collecting light returning from the selected inspection region under illumination over time and generating data indicative of detected variations in collected light intensity;
 wherein the illuminator comprises one or more light sources arranged to define multiple illumination paths arranged symmetrically with respect to the detection path, and 
 wherein the illuminator is controllably operable to provide simultaneous multi-directional constant illumination of said selected wavelength range of said selected inspection region along said multiple illumination paths under symmetrical illumination conditions with respect to the detection path, thereby providing uniformity of the illumination during collection of the light returning from the selected inspection region along said detection path, 
 thereby providing that the detected variations in intensity of light being collected over time from the selected inspection region subjected to the constant illumination under the symmetrical illumination conditions are indicative of variation of light returned from the selected inspection region with compensation of variations of backscattering of illuminating light caused by a change of orientation of the inspection region and reduced variation in reflected intensity caused by movement of the inspection region. 
 
     
     
       2. The system of  claim 1 , further comprising a control unit configured for receiving input data indicative of the detected variations in the collected light intensity at a selected sampling rate and for processing the input data for determining data indicative of at least one of the following biomechanical parameters of a patient: PPG, SpO 2 , heart rate. 
     
     
       3. The system of  claim 1 , wherein said illuminator comprises a circular light source and wherein said at least one detector is located around a center of a circle defined by the light source. 
     
     
       4. The system of  claim 1 , wherein said illuminator comprises two or more light sources arranged at equal distance in symmetrical arrangement with respect to the detection path. 
     
     
       5. The system of  claim 1 , further comprising a control unit configured for receiving and processing input data indicative of said variations in the collected light intensity detected under the symmetrical illumination conditions and being associated with expansion or contraction of blood vessels at the inspection region, and generating output data indicative of cardiovascular blood volume pulse, enabling photoplethysmographic measurements. 
     
     
       6. The system of  claim 1 , further comprising a control unit configured for receiving and processing input data indicative of said variations in the collected light intensity detected under the symmetrical illumination conditions and being associated with expansion or contraction of blood vessels at the inspection region, and generating output date indicative of SpO 2  thereby enabling blood oxidization measurements. 
     
     
       7. The system of  claim 1 , wherein said illuminator is configured for illuminating a selected number of two or more inspection regions to provide the constant illumination under the symmetrical illumination conditions for each of said two or more inspection regions, and said at least one detector comprises two or more detectors configured for collecting light returning from corresponding two or more of said inspection regions being illuminated and for detecting variations in collected light intensity for each of said selected number of two or more regions. 
     
     
       8. The system of  claim 7 , comprising a controller configured for receiving input data comprising said variations in collected light intensity for each of said selected number of two or more regions, and for determining one or more biomedical parameters utilizing averaging of data collected from the two or more regions. 
     
     
       9. The system of  claim 1 , wherein said illuminator comprises a plurality of two or more light sources, said plurality of two or more light sources comprises light sources configured for emitting light of at least first and second different wavelengths within said selected wavelength range.